1. FIELD OF THE INVENTION
The present invention concerns an oven for burning in electronics modules, in other words for operating a batch of electronics modules for a sufficient time to eliminate those subject to premature failure.
2. DESCRIPTION OF THE PRIOR ART
Burning in is carried out at raised temperature so that the modules operate under extreme junction temperature conditions, either at constant temperature or according to predetermined thermal cycles.
Until now this operation has been carried out by placing the modules in a ventilated oven the temperature in which is regulated in the conventional way by a thermostat device.
This prior art method has the disadvantage of a highly non-uniform distribution of temperature where the modules dissipate a significant amount of heat (more than 10 W). The various modules in the oven are therefore subject to varying thermal stresses, excessive in some cases and insufficient in others.
This drawback is accentuated in the case of dynamic burning in whereby the module is operated for a first period at moderate dissipation and then for a second period at maximum dissipation. Given that not all the modules are placed in the oven at the same time, and therefore do not begin the burning in cycle simultaneously, there are simultaneously in the oven modules in the low dissipation mode and others in the high dissipation mode, which further accentuates temperature differentials within the oven, contrary to its primary function.
One object of the invention is to propose an oven for burning in large batches of modules (several dozen or several hundred at a time) with all modules undergoing uniform thermal stresses.
Another object of the invention is to propose a burning in oven enabling the temperature to be regulated individually at each module so that all modules are burned in under exactly the same conditions.
The basic principle of the invention is to apply to the cooling heatsink of each module a heat shunt having a male comb shape matching the shape of the module heatsink, the external surface of the heat shunt being provided with a heatsink whose design dissipation capacity is greater than that of any module to be tested.
The temperature of each module can be regulated locally and is not dependent on the uniformity of the temperature within the oven.
As regulation will always be required (whether heat is supplied to or removed from the module), the controlled heating element will compensate for the greater or lesser quantity of heat that the heatsink of the block would dissipate given the local temperature of its environment, that is to say the local temperature within the oven.